These issues are not specific to this player, but since they get asked a lot...

This is intended for absolute beginners.

What are some recommended calibration discs?

I'm dealing only with simple adjustments of Brightness, Contrast, Saturation and Tint done by eye, which is what I do. If you have electronic meters or are hiring professional help, you don't need my advice.
For much more information, see the AVSForum Calibration Forum.
Some displays have a blue-only calibration mode. If yours doesn't, you'll need a blue filter to set the Saturation and Tint properly. Retail calibration discs come with a filter, but the THX filter glasses are very handy and recommended: $1.99 + shipping. (Shipping is more like $2.50, not the $10-12 shown on the page).

Using the Spears & Munsil Calibration Filter I have used the DVE HD Basics disc. It has a large amount of tutorial material and includes audio tests.But my main tool is the free downloadable AVS HD 709 disc. It has no tutorial material on the disc and no audio tests. But once you have learned the basic procedures, most likely by practicing with other discs first, it is quick and pleasant to use. It is sort of a Blu-ray equivalent to the GetGray DVD, although with many more patterns. Documentation is in the AVS HD 709 patterns file.THX Optimizer is included for free on many DVDs and is starting to appear on Blu-ray. Here is a page to search for THX Optimizer titles.Sony/Columbia discs have a secret set of patterns. From the main menu press 7669really fast. I haven't spent much time with them.

If you are new to calibration and totally lost or not getting any results, here is my advice:

Get the THX filter glasses and practice with the THX Optimizer. It is easy to use and has simple on-screen help.
Use it for a few weeks or months. Once you have practice and experience with that, all the other calibration discs will make more sense.

Do I adjust the player or the display?

The standard advice is to adjust the display unless you have some specific reason not to. The display is likely to have finer adjustment controls than the player.

Do I need to calibrate the display for every input device?

Yes.

Can I use a DVD calibration disc to adjust Blu-ray settings?

DVD and Blu-ray use the same grayscale standard, so Brightness and Contrast should be the same on DVD and Blu-ray calibration discs.
Blu-ray uses a slightly different color standard than DVD, but if the player converts the signal properly when upscaling, a DVD calibration disc should work well enough for a Blu-ray player. All the OPPO players do the correct color standard conversion.
However, since a free Blu-ray calibration disc (AVS HD 709) is available, I would use that, especially for color adjustment.

What is Y/C Delay?

The luma (black-and-white) and chroma (color) channels of a video signal must be synced up when they are displayed or image artifacts will appear. See the Guide to the Progressive Scan Shootouts for details.
The Y/C Delay control adjusts this timing.
The calibration DVDs include Y/C test patterns, but the only Blu-ray version I have is on the Spears & Munsil disc.

Do I need to calibrate if my display has already been professionally calibrated?

The user controls (brightness, contrast, saturation) still need to be adjusted for each input device.

How do I calibrate when my system does not pass Blacker-than-Black or Whiter-than-White?

Many users will not have the problems passing the Blacker Than Black and Peak White data anticipated by these comments, but this approach to setting up gray scale levels will work whether or not your setup has that problem.
First of all, try the alternate data formats from the OPPO to your AVR and from your AVR to your display. Some devices only clip YCbCr or only clip RGB.

Note

If you use what the OPPO calls RGB PC Level there is no place in the data format for Blacker than Black (BTB) or Peak White (PW) data so they will, necessarily, be clipped. Other devices often call this format something like "Extended RGB" or even "Enhanced RGB" although there's certainly no reason to prefer it for home theater use. The PS3 calls it "RGB Full" (although the PS3 has a bug that even clips BTB and PW data when using "RGB Limited").

What the OPPO calls RGB Video Level and others usually call "Studio RGB" will pass BTB and PW data to properly engineered and set up receivers and displays. For some background on what's going on in these data formats and some hints as to why you might prefer one over the other when paired with particular hardware, see What if I want to set the color space manually?

Again, it is worth trying to find a way to set up your hardware to pass BTB and PW data, but with some AVRs and displays you just won't be able to do it.

In that case you can still use the Spears & Munsil disc to calibrate your video levels.

I'm going to assume you are directly connected to a display. If connected through an AVR, you have an additional point of adjustment.

The first suggestion is that you leave the OPPO's Picture Adjustment settings at their factory default values. Try calibrating using only the controls in your Display. If that doesn't provide a complete solution, next look for level adjustment settings in your AVR. If that also doesn't provide a complete solution, or if you are having problems coming up with display/AVR settings that work for all your source devices (and your display/AVR don't provide separate memory settings for use with different devices), then, finally, use the controls in the OPPO.

The reason for this is that the OPPO puts out "correct" levels at its default settings. So if you find things are not right using those default settings then that's an indication there is something wrong in the settings in your display and/or AVR.

One more preliminary

The factory default settings in most displays are flat out wrong for best quality viewing. These are the justifiably disparaged "torch mode" settings -- way too bright and contrasty, overly sharpness "enhanced", way too blue a color temperature, and overly red pushed to compensate for the faulty color temperature. The "torch mode" settings are designed to be eye catching in garish store lighting. So do not hesitate to move away, often far away, from the factory default settings.

Everybody has to do that.

Many modern displays offer "picture modes" that are different combos of factory default settings. Avoid like the plague any modes labeled "vibrant", "dynamic", "scorch your eyeballs" or the like. Try to find one labeled "movies".

If you can't figure out which to use, pick the one that looks darkest and softest and start from there. And don't assume you can pick just any "picture mode" and alter it via user settings to be correct. "Picture modes" often make hidden setting changes in the background that you can not alter from the user controls. So find the correct "picture mode" to begin with and make your adjustments from there.

So again, assuming you are directly connected to a display:

You will use the Brightness control in the display to adjust Black levels (a good way to remember this is that they both start with "B").

You will use the Contrast (or Picture) control to control White levels.

The two controls interact so you will need to iterate to find the sweet spot setting for both of them that works best.

The next thing you need to know is that the data coming off an SD-DVD or Blu-ray disc encodes "Black" as digital 16 and "Reference White" as digital 235. The range from 1 to 15 is the Blacker than Black data (not intended to be seen) and the range from 236 to 254 is the Peak White data (intended to be seen but not essential). 0 and 255 are reserved values.

The Spears & Munsil charts actually label blocks that have been encoded with values above and below Black and Reference White.

Use the Dynamic Range Low chart for a best look at Black levels.

Use the Dynamic Range High chart for a best look at White levels.

Use the Contrast chart to view both at the same time in an image that's got a kind of "in between" average image brightness.

So what you do is lower the Brightness control until 17 and above become invisible (blend into the black background) and then raise it until 18 becomes slightly visible (and perhaps just the slightest hint of parts of 17 are also visible -- i.e., a few "dither pixels" light up). Note that you should not see 16 = Black or below. All of that data should merge into one, uniform, indistinguishable "Black". Also note that you will need to check this sort of thing in a darkened room.

Note

Some displays have "floating" black levels that vary according to the average brightness on screen. So if you look at say the Pluge Low and Pluge High charts you may see a distinct change in your effective black levels. Some such displays have dynamic brightness or automatic brightness settings that can be turned off to prevent this. If not, you will need to pick a compromise Brightness setting that works well across a range of content for you. Typically you would target a lower Brightness setting that works well in dark scenes so that you don't see noise in dark scenes -- at the expense of losing some "near black" details in brighter scenes.

At the other end, lower Contrast quite a bit. The bright blocks in the Dynamic Range High chart should be visible although you won't see any above 234 due to the clipping in your display or AVR. Now raise Contrast until whites have a pleasing "whiteness" to them rather than looking grayish, but don't raise it so far that you lose the ability to distinguish the blocks at and below 234. If those blocks at and below 234 start to blend into one common "white", lower Contrast until they become visible again.

Note

If your display and AVR don't clip the BTB and PW data you still want to adjust Black levels so that 16 and below are completely invisible. At the other end, see if you can find a Contrast setting that is high enough to give a pleasing "whiteness" to whites but also low enough so that you can distinguish the Peak White blocks all the way up to 252 or even 253. The "correct" Contrast setting will almost certainly be quite a bit lower than its factory default setting.

You may find that you have a small set of Brightness/Contrast pairs that look equally good. If so, you can choose between those pairs by viewing the gray scale ramp on the Contrast chart. Pick the pair that produces the smoothest look to the ramp -- the least amount of "banding".

Brightness and Contrast control the end points of the gray scale ramp. The response of the display to values between Black and Reference White is controlled by the Gamma setting. Many modern displays have Gamma set too low by factory default as this gives "false pop" to the imaging in stores. Just another "torch mode" setting.

Adjusting Gamma is complicated. Doing it right requires an optical sensor tool. Nobody has much luck trying to do full Gamma curve adjustments by eye alone -- although some displays offer a single, all in one Gamma adjustment that may prove helpful. So I'll only point out here that if you do adjust Gamma you will probably find that Gamma, Brightness, and Contrast all interact. So you will need to iterate -- re-checking Brightness and Contrast as you adjust Gamma. (Proper Gamma correction is a major factor in eliminating "banding" or "false contours" in your video. So it is worth the effort to get right. But as I said, this is complicated).

There's a whole Calibration Forum here. Check out the sticky threads in that forum for additional suggestions.

Why aren't displays calibrated correctly at the factory?

Old joke:

Spectator: Say, Mister, how do you tune that banjo?
Banjo Player (outraged): What do you mean? I bought this thing tuned!

A/V gear has adjustment controls for a reason -- the units need to be adjusted to compensate for: